---
kind: "section"
citation: "1 C.F.R. § 601.17"
title: "1"
number: "601.17"
heading: "Supplemental Environmental Assessments."
url: "https://uscodex.org/cfr/1/601.17"
---

# §601.17. Supplemental Environmental Assessments.

- (a) The NCPC shall prepare a supplemental EA if five or more years have elapsed since adoption of the EA and:
  - (1) There are substantial changes to the proposed action that are relevant to environmental concerns; or
  - (2) There are significant new circumstances or information that are relevant to environmental concerns and have a bearing on the proposed action or its impacts.
- (b) The NCPC may supplement a Draft or Final EA at any time to further the purposes of NEPA.
- (c) The NCPC shall prepare, circulate, and file a supplement to a Draft or Final EA, and adopt a FONSI in accordance with the requirements of §§ [601.15](/cfr/1/601.15.md) and [601.16](/cfr/1/601.16.md). If NCPC is not the Lead Agency, it shall proceed as outlined in § [601.16(b)](/cfr/1/601.16.md?p=b) and [(c)](/cfr/1/601.16.md?p=c).

## Notes

### Authority

Authority: 42 U.S.C. 4371; 40 CFR 1507.3

### Source

Source: 82 FR 45424, Sept. 29, 2017; 82 FR 48609, Oct. 19, 2017, unless otherwise noted.